Evaluation of Wormhole Routed Networks under Hybrid Traac Loads 1

We investigate the performance of wormhole-routed networks under hybrid traac loads to examine the impact of long and short messages on each other. The short messages not only experience increased average latency but also experience a large increase in the variance of that latency. The negative performance impact of long messages increases proportionally with both the fraction and size of the long messages. We also explore two techniques: virtual lanes and adap-tive routing to improve network performance under the hybrid traac loads. Performance losses due to long messages can be dramatically reduced with either technique. The two techniques are complementary, so employing them simultaneously yields the best performance of all, virtually eliminating performance losses experienced by short messages. This means that pack-etization may not be necessary in such networks.